Grok 4.5 vs Claude Opus 4.8
Musk called Grok 4.5 "an Opus-class model, but faster, more token-efficient and lower cost." Here's the claim against Anthropic's actual Opus — pricing, context and the published numbers, side by side.
Grok 4.5 vs Claude Opus 4.8: side-by-side
| Grok 4.5 | Claude Opus 4.8 | |
|---|---|---|
| Maker | SpaceXAI (formerly xAI) | Anthropic |
| Released | 9 July 2026 | 27 May 2026 |
| Tier | Workhorse ("Opus-class" positioning) | Flagship |
| Context window | 500,000 tokens | 1,000,000 tokens |
| Max output | Not specified | Up to 128,000 tokens |
| API price (per 1M) | $2 / $6 per 1M tokens | $5 / $25 per 1M tokens |
| Speed | ~80 output tokens/second | Fast mode: up to 2.5x output speed at $10/$50 |
| Access | Proprietary — xAI API console, Grok Build, Cursor, OpenRouter · EU pending (later July 2026) | Proprietary — Claude API & claude.ai |
| Best at | Coding, office/clerical work, research at low cost per task | Long-horizon agentic work, coding, knowledge work |
| Standout | Token efficiency — ~4.2x fewer output tokens per SWE-bench Pro task than Opus 4.8 (max) | 1M context, adaptive thinking, dynamic workflows with parallel subagents |
Price comparison
| Model | Input (per 1M) | Output (per 1M) |
|---|---|---|
| Grok 4.5 | $2.00 | $6.00 |
| Claude Opus 4.8 | $5.00 | $25.00 |
| Claude Opus 4.8 (fast mode) | $10.00 | $50.00 |
Estimate your monthly API cost for Grok 4.5 vs Claude Opus 4.8 with the LLM API pricing calculator →
Published benchmark figures
The figures below are from SpaceXAI's Grok 4.5 launch chart (as reported by independent coverage) — the one place both models appear on the same suites. Vendor-published head-to-heads favour the vendor's chosen suites; treat accordingly. Anthropic's own Opus 4.8 materials describe benchmark improvements without publishing per-suite figures.
| Benchmark | Grok 4.5 | Claude Opus 4.8 |
|---|---|---|
| SWE-bench Pro | 64.7% | 69.2% |
| DeepSWE 1.1 | 53% | 59% |
| Avg output tokens per SWE-bench Pro task | 15,954 | 67,020 (max effort) |
Grok 4.5 also beat Opus 4.8 on DeepSWE 1.0 and Terminal-Bench 2.1 (83.3%) in the same chart, per SpaceXAI — a 2-2 split across the four suites shown.
What the table says
- Pricing. Grok 4.5 lists at $2 / $6 per 1M tokens; Claude Opus 4.8 at $5 / $25. That is 2.5x cheaper input and ~4.2x cheaper output — and Grok 4.5's measured token efficiency (~4.2x fewer output tokens per SWE-bench Pro task) multiplies the gap in cost per solved task.
- Capability. On the published numbers the "Opus-class" claim is defensible but not dominant: a 2-2 benchmark split, with Opus 4.8 ahead on the two hardest suites (SWE-bench Pro, DeepSWE 1.1).
- Context. Opus 4.8 doubles Grok 4.5's window — 1M vs 500K tokens — which matters for monorepo-scale and long-document work.
- Access. Both are proprietary hosted APIs; Grok 4.5 additionally has no EU availability until later in July 2026.
Key takeaway
If your workload is high-volume, cost-sensitive coding or knowledge work, Grok 4.5's price-times-efficiency math is hard to beat. If you need the last few benchmark points, 1M context or EU availability today, Opus 4.8 keeps the premium seat. Run your own volumes through the pricing calculator to see the monthly difference.
Full Grok 4.5 overview Full Claude Opus 4.8 overview
Frequently asked questions
Which is cheaper, Grok 4.5 or Claude Opus 4.8?
Grok 4.5 — $2 / $6 per 1M tokens versus $5 / $25: 2.5x cheaper input, ~4x cheaper output, before counting token efficiency.
Is Grok 4.5 as good as Claude Opus 4.8?
On SpaceXAI's own chart they split four coding benchmarks 2-2, with Opus 4.8 ahead on SWE-bench Pro (69.2% vs 64.7%) and DeepSWE 1.1 (59% vs 53%). Close, not a clean win.
Which has the bigger context window?
Claude Opus 4.8 — 1,000,000 tokens versus 500,000 for Grok 4.5.
Can I run either locally?
No — both are proprietary models accessed through their vendors' APIs; neither publishes weights.